Extraction of Rare-Earth Metals During the Systematic Processing of Diaspore-Boehmite Bauxites

Abstract

An integrated technology is proposed for processing diaspore-boehmite bauxites and extracting their useful components. It is established that sintering bauxite with a caustic alkali increases the quantities of rare-earth metals that are recovered. Experiments showed that the sintering of bauxite with a caustic alkali must be done with no more than 10–15% moisture in the charge at the optimum temperature of 200°C. Leaching of the sinter cake with water or a dilute aluminate solution forms high-iron red mud with low concentrations of alkali and alkaline-earth metals. Leaching the mud with a dilute inorganic acid makes it possible to extract up to 90% of the rare-earth metals, including scandium oxide.